Well, considering most people would expect the masculine pronoun "him" in the indefinite third person, I don't think it's much of a stretch. I've literally never seen an unknown person referred to as "her" or "she" alone, without any prior indication. I'm fond of "her or him," personally. I didn't realize you were such a hardcore feminist that you would naturally use "she" or "her" for unknown people without provocation. Good luck with that one.

Of course, I'm not much of an English guy so maybe there's been a massive shift towards "her" and "she" that I've been totally unaware of.